An Improved Method for Fabrication of Ag-GO Nanocomposite with Controlled Anti-Cancer and Anti-bacterial Behavior; A Comparative Study

Abstract

In this study, two green procedures for Silver-Graphene Oxide (Ag-GO) nanocomposite synthesis were investigated. As a common method, AgNO 3 was first loaded on the GO surface and then was reduced and stabilized by walnut green husk extract, producing Ag-GO-І. As an innovative approach, GO was first exposed to the extract and then the AgNO 3 was added as the second step, producing Ag-GO-П. Physicochemical properties, antibacterial and cytotoxicity activity of both nanocomposites were subsequently studied comparing with free silver nanoparticles (AgNPs) and pure GO. Based on the results, exposure of GO to the extract, as a reducing agent, at the first/last step of the synthesis process resulted in the fundamental differences in the final products. So that, high amounts of agglomerated silver nanoparticles were formed between the GO sheets, when using the common method, whereas in Ag-GO-П, small AgNPs were formed on the GO sheets without aggregation, entirely covering the sheets. Antibacterial and cytotoxic behavior of these nanomaterials could be compared as AgNPs > Ag-GO-П > Ag-GO-І. It is assumed that these differences are due to control of unwanted nucleation in the synthesis process that Ag nanoparticles are smaller with less agglomeration when the GO surfaces are pre-treated with reducing agent.

Photocatalytic activity and antibacterial properties of linen fabric using reduced graphene oxide/silver nanocomposite

“…GO sheets have a high specic surface area, which makes them an outstanding platform for stabilizing silver nanoparticles. 30 Upon immersing the fabrics in a solution of silver nitrate, electrostatic interaction facilitates the attraction between the negatively charged oxygen atoms of hydroxyl (OH À ) and carboxyl (COO À ) groups of the GO-coated cellulosic fabrics and the positively charged silver ions (Ag + ). Under heating and stirring conditions, trisodium citrate permits the formation of silver nanoparticles by the concurrent in situ reduction of Ag + ions to Ag 0 .…”

“…The signicant level of antibacterial activity of RGO/Ag nanocomposites is related to the presence of silver nanoparticles. 30 The improvement in the activities might be recognized as being due to the modulation or adsorption of the RGO nanosheets by Ag ions, since silver nanoparticles were placed on the surface of the RGO platform, such that they were directly exposed to the bacterial cells. The GO sheets prohibited the aggregation and enlargement of silver nanoparticles; thus enhancing the composite performance.…”

Antibacterial Activities of Aliphatic Polyester Nanocomposites with Silver Nanoparticles and/or Graphene Oxide Sheets

“…Furthermore, AgNPs inhibit aggregation and restacking of graphene sheet. Fined AgNPs are dispersed uniformly on the GO surface compared with large AgNPs produced without GO template (Figure 3) [132,133,134].…”

“…The GO-AgNPs nanocomposites exhibit excellent antibacterial activity against several gram-negatives and gram-positives [134,135,136,137,138]. Colloidal GO-AgNPs are capable of killing P. aeruginosa by releasing Ag + ions from finely dispersed AgNPs.…”

“…Their bactericidal activity is dose- and time-dependent (Figure 4a). A marked reduction in bacterial growth is observed at GO-AgNPs contents of 2.5 and 5.0 µg/mL for 30–60 min [134]. The GO-AgNPs nanocomposites can generate higher ROS level than AgNPs or GO alone upon exposure to S. pneumonia and Shigella flexneri strains [136].…”